Plan the perfect garden with our interactive tool →

Are Four O'Clocks Perennials?

Four o'clock (Mirabilis jalapa) is a heat-loving plant with trumpet-shaped red, yellow, purple, pink or mahogany blooms that open in late afternoon. The flower depends on moths and butterflies for pollination. Four o'clock, which grows from underground tubers, is perennial in warm climates, but survives only with special treatment in cool climates.

Hardiness Zones

Four o'clock is a tender perennial, meaning that the plant doesn't tolerate cold weather. Other tender perennials include dahlia, canna lily, impatiens, coleus and tuberous begonia. Four o'clock is perennial in U.S. Department of Agriculture hardiness zones 10 and above, which means that four o'clock may survive temperatures as low as 30 degrees Fahrenheit with proper care, but will be killed by colder temperatures. In borderline climates of zones 8 and 9, four o'clock is often winterized in the ground. In colder climates, four o'clock's long tubers are stored during the winter.

Winterizing Four O'Clock

Four o'clock survives in the ground with a good protective winter covering in hardiness zones 8 and 9. To winterize the plant, water the soil deeply enough to saturate the tubers before the first frost in autumn. Clip off dry and dead growth to within 3 inches of ground level after the ground freezes, then cover the plant with 4 to 5 inches of mulch such as straw, pine needles or dry, chopped leaves. Avoid using wet leaves as mulch, as the leaves become compacted and prevent water and air from reaching the tubers. Remove the mulch as soon as shoots poke through it in the spring.

  • Four o'clock is a tender perennial, meaning that the plant doesn't tolerate cold weather.
  • Four o'clock survives in the ground with a good protective winter covering in hardiness zones 8 and 9.

Digging Four O'Clocks

Four o'clocks have sturdy underground tubers that make them good candidates for overwintering and replanting in spring. To overwinter, cut the plants back to 3 to 4 inches above ground level after the foliage is nipped by a light frost. Dig the tubers carefully with a garden fork. Dig deeply, as the carrot-like tubers can measure more than 12 inches in length.

Storing Tubers

Rinse the tubers with a garden hose, then place them in a shady, well-ventilated spot to dry for two weeks. Bury the tubers in a cardboard box filled with peat moss or vermiculite, then store them in a dry room where the temperature will be maintained between 35 and 40 degrees. Replant the tubers after all danger of frost has passed in spring.

  • Four o'clocks have sturdy underground tubers that make them good candidates for overwintering and replanting in spring.
  • Replant the tubers after all danger of frost has passed in spring.

Related Articles

How to Care for a Caladium Plant in the Winter
How to Care for a Caladium Plant in the Winter
Care of Crocosmia
Care of Crocosmia
How to Water & Care for Elephant Ears
How to Water & Care for Elephant Ears
How to Take Care of Cannas
How to Take Care of Cannas
How to Care for a Cannis Flower
How to Care for a Cannis Flower
How to Plant Ranunculus Indoors
How to Plant Ranunculus Indoors
How to Winterize Dahlia Tubers
How to Winterize Dahlia Tubers
How to Grow a Bearded Iris in Zone 9
How to Grow a Bearded Iris in Zone 9
How to Winterize Your Foxglove Flowers
How to Winterize Your Foxglove Flowers
Care for Cannas in Zone 8
Care for Cannas in Zone 8
Overwintering a Begonia
Overwintering a Begonia
How to Transplant Crocosmia Lucifer
How to Transplant Crocosmia Lucifer
How to Plant Dahlia Tubers in Zone 5
How to Plant Dahlia Tubers in Zone 5
How to Care for a Tuberose
How to Care for a Tuberose
Garden Guides
×